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MDL-36466 cache: improved handling of exceptions during initialisation.

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This commit is contained in:
Sam Hemelryk 2012-11-13 09:26:07 +13:00
parent f42c34a38a
commit 7383a7e2a0
4 changed files with 127 additions and 13 deletions
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10
cache/classes/config.php vendored
View File

@ -122,12 +122,15 @@ class cache_config {
/**
* Loads the configuration file and parses its contents into the expected structure.
*
* @param array|false $configuration Can be used to force a configuration. Should only be used when truly required.
* @return boolean
*/
public function load() {
public function load($configuration = false) {
global $CFG;
$configuration = $this->include_configuration();
if ($configuration === false) {
$configuration = $this->include_configuration();
}
$this->configstores = array();
$this->configdefinitions = array();
@ -425,7 +428,8 @@ class cache_config {
*/
public function get_stores_for_definition(cache_definition $definition) {
// Check if MUC has been disabled.
if (defined('NO_CACHE_STORES') && NO_CACHE_STORES !== false) {
$factory = cache_factory::instance();
if ($factory->is_disabled()) {
// Yip its been disabled.
// To facilitate this we are going to always return an empty array of stores to use.
// This will force all cache instances to use the cachestore_dummy.

74
cache/classes/factory.php vendored
View File

@ -40,6 +40,19 @@ defined('MOODLE_INTERNAL') || die();
*/
class cache_factory {
/** The cache has not been initialised yet. */
const STATE_UNINITIALISED = 0;
/** The cache is in the process of initialising itself. */
const STATE_INITIALISING = 1;
/** The cache is in the process of saving its configuration file. */
const STATE_SAVING = 2;
/** The cache is ready to use. */
const STATE_READY = 3;
/** The cache encountered an error while initialising. */
const STATE_ERROR_INITIALISING = 9;
/** The cache has been disabled. */
const STATE_DISABLED = 10;
/**
* An instance of the cache_factory class created upon the first request.
* @var cache_factory
@ -82,6 +95,12 @@ class cache_factory {
*/
protected $lockplugins = null;
/**
* The current state of the cache API.
* @var int
*/
protected $state = 0;
/**
* Returns an instance of the cache_factor method.
*
@ -91,6 +110,10 @@ class cache_factory {
public static function instance($forcereload = false) {
if ($forcereload || self::$instance === null) {
self::$instance = new cache_factory();
if (defined('NO_CACHE_STORES') && NO_CACHE_STORES !== false) {
// The cache stores have been disabled.
self::$instance->set_state(self::STATE_DISABLED);;
}
}
return self::$instance;
}
@ -113,6 +136,8 @@ class cache_factory {
$factory->configs = array();
$factory->definitions = array();
$factory->lockplugins = null; // MUST be null in order to force its regeneration.
// Reset the state to uninitialised.
$factory->state = self::STATE_UNINITIALISED;
}
/**
@ -253,9 +278,19 @@ class cache_factory {
$class = 'cache_config_phpunittest';
}
$error = false;
if ($needtocreate) {
// Create the default configuration.
$class::create_default_configuration();
// Update the state, we are now initialising the cache.
self::set_state(self::STATE_INITIALISING);
$configuration = $class::create_default_configuration();
if ($configuration !== true) {
// Failed to create the default configuration. Disable the cache stores and update the state.
self::set_state(self::STATE_ERROR_INITIALISING);
$this->configs[$class] = new $class;
$this->configs[$class]->load($configuration);
$error = true;
}
}
if (!array_key_exists($class, $this->configs)) {
@ -264,6 +299,11 @@ class cache_factory {
$this->configs[$class]->load();
}
if (!$error) {
// The cache is now ready to use. Update the state.
self::set_state(self::STATE_READY);
}
// Return the instance.
return $this->configs[$class];
}
@ -338,4 +378,36 @@ class cache_factory {
$class = $this->lockplugins[$type];
return new $class($name, $config);
}
/**
* Returns the current state of the cache API.
*
* @return int
*/
public function get_state() {
return $this->state;
}
/**
* Updates the state fo the cache API.
*
* @param int $state
* @return bool
*/
public function set_state($state) {
if ($state <= $this->state) {
return false;
}
$this->state = $state;
return true;
}
/**
* Returns true if the cache API has been disabled.
*
* @return bool
*/
public function is_disabled() {
return $this->state === self::STATE_DISABLED;
}
}

49
cache/locallib.php vendored
View File

@ -41,6 +41,14 @@ defined('MOODLE_INTERNAL') || die();
*/
class cache_config_writer extends cache_config {
/**
* Switch that gets set to true when ever a cache_config_writer instance is saving the cache configuration file.
* If this is set to true when save is next called we must avoid the trying to save and instead return the
* generated config so that is may be used instead of the file.
* @var bool
*/
protected static $creatingconfig = false;
/**
* Returns an instance of the configuration writer.
*
@ -53,6 +61,10 @@ class cache_config_writer extends cache_config {
/**
* Saves the current configuration.
*
* Exceptions within this function are tolerated but must be of type cache_exception.
* They are caught during initialisation and written to the error log. This is required in order to avoid
* infinite loop situations caused by the cache throwing exceptions during its initialisation.
*/
protected function config_save() {
global $CFG;
@ -61,20 +73,15 @@ class cache_config_writer extends cache_config {
if ($directory !== $CFG->dataroot && !file_exists($directory)) {
$result = make_writable_directory($directory, false);
if (!$result) {
throw new cache_exception('ex_configcannotsave', 'cache', '', null, 'Cannot create config directory.');
throw new cache_exception('ex_configcannotsave', 'cache', '', null, 'Cannot create config directory. Check the permissions on your moodledata directory.');
}
}
if (!file_exists($directory) || !is_writable($directory)) {
throw new cache_exception('ex_configcannotsave', 'cache', '', null, 'Config directory is not writable.');
throw new cache_exception('ex_configcannotsave', 'cache', '', null, 'Config directory is not writable. Check the permissions on the moodledata/muc directory.');
}
// Prepare a configuration array to store.
$configuration = array();
$configuration['stores'] = $this->configstores;
$configuration['modemappings'] = $this->configmodemappings;
$configuration['definitions'] = $this->configdefinitions;
$configuration['definitionmappings'] = $this->configdefinitionmappings;
$configuration['locks'] = $this->configlocks;
$configuration = $this->generate_configuration_array();
// Prepare the file content.
$content = "<?php defined('MOODLE_INTERNAL') || die();\n \$configuration = ".var_export($configuration, true).";";
@ -106,6 +113,20 @@ class cache_config_writer extends cache_config {
}
}
/**
* Generates a configuration array suitable to be written to the config file.
* @return array
*/
protected function generate_configuration_array() {
$configuration = array();
$configuration['stores'] = $this->configstores;
$configuration['modemappings'] = $this->configmodemappings;
$configuration['definitions'] = $this->configdefinitions;
$configuration['definitionmappings'] = $this->configdefinitionmappings;
$configuration['locks'] = $this->configlocks;
return $configuration;
}
/**
* Adds a plugin instance.
*
@ -293,6 +314,9 @@ class cache_config_writer extends cache_config {
*
* This function calls config_save, however it is safe to continue using it afterwards as this function should only ever
* be called when there is no configuration file already.
*
* @return true|array Returns true if the default configuration was successfully created.
* Returns a configuration array if it could not be saved. This is a bad situation. Check your error logs.
*/
public static function create_default_configuration() {
global $CFG;
@ -357,7 +381,16 @@ class cache_config_writer extends cache_config {
'default' => true
)
);
$factory = cache_factory::instance();
// We expect the cache to be initialising presently. If its not then something has gone wrong and likely
// we are now in a loop.
if ($factory->get_state() !== cache_factory::STATE_INITIALISING) {
return $writer->generate_configuration_array();
}
$factory->set_state(cache_factory::STATE_SAVING);
$writer->config_save();
return true;
}
/**

7
lib/setuplib.php
View File

@ -1444,7 +1444,12 @@ border-color:black; background-color:#ffffee; border-style:solid; border-radius:
width: 80%; -moz-border-radius: 20px; padding: 15px">
' . $message . '
</div>';
if (!empty($CFG->debug) && $CFG->debug >= DEBUG_DEVELOPER) {
// Check whether debug is set.
$debug = (!empty($CFG->debug) && $CFG->debug >= DEBUG_DEVELOPER);
// Also check we have it set in the config file. This occurs if the method to read the config table from the
// database fails, reading from the config table is the first database interaction we have.
$debug = $debug || (!empty($CFG->config_php_settings['debug']) && $CFG->config_php_settings['debug'] >= DEBUG_DEVELOPER );
if ($debug) {
if (!empty($debuginfo)) {
$debuginfo = s($debuginfo); // removes all nasty JS
$debuginfo = str_replace("\n", '<br />', $debuginfo); // keep newlines